| In order to explore the application value of biochar in the treatment of As and Cd contaminated soils,two types of Cd-contaminated soils(mainly single-heavy(Cd))were selected as the soil amendment.Cadmium contaminated soil and heavy As and Cd complex contaminated soils.The effects of application of corn stalk biochar on soil As and Cd activity and uptake of As and Cd were studied by soil culture experiment and outdoor pot experiment.The main test results are as follows:(1)The effect of corn stover biochar(1% addition)at different preparation of temperatures(300?,400?,500?)on the pH value,oxidation-reduction potential and the arsenic and cadmium contents of paddy soil of arsenic-cadmium complex pollution,in a waterlogged environment,were studied by indoor soil incubation.The experiment was carried out for four treatments: CK,CB-300,CB-400 and CB-500.The results showed that the addition of corn straw biocoke could increase the soil pH value by 0.2 ~ 1.24 units,CB-500 treatment to improve the most significant pH,up to 1.24 units;compared with CK;The redox potential of soil in flooded environment decreased rapidly,and there was significant difference between different treatments,the higher the temperature of biocarbon preparation,the more obvious the reduction effect and the redox potential reached the lowest at 96 th day;With the prolongation of culture time,the weak acid extracted and oxidizable cadmium in the soil were gradually transferred to the residual and cadmium;The contents of arsenic,Ca-bound,Al-bound and Fe-bound arsenic in the soil were increased and the arsenic content in the residual soil decreased with the increase of arsenic content in the soil.(2)In order to investigate the effect of corn straw biocarbon and corn straw powder on the migration of As and Cd in rice,the effects of 1% corn stalk powder(CS)and arsenic-cadmium compound polluted soil(CB-300,CB-400,CB-500)were used to analyze the changes of As and Cd contents in different parts or organs of rice at tillering stage,heading stage and Maturity stage.The effects of adding materials on rice yield were analyzed.The results shows,the contents of As and Cd in rice at different stages were: root> stem> leaf> brown rice;The addition of corn straw powder and corn straw bio-char could prevent the migration of As and Cd into rice plants,Compared with CK,the contents of Cd in different parts of rice were significantly decreased in all treatments(P <0.05),and the treatment of CB-500 was the best in the three key growth stages;The application of corn straw bio-char could decrease the content of As in different parts of rice,but the treatments did not reach the significant level;Compared with CK,application of corn stalk bio-carbon and corn straw powder can increase rice yield,rice yield 6.93% ~55.36%,The effectiveness of Cd is getting lower and lower.The results can provide theoretical basis and data support for biological carbon control of arsenic and cadmium compound pollution soil and rice safety production.(3)The effects of different modifiers on the uptake and accumulation of Cd were studied by adding activated carbon,mineral silicon and microbial agents to a single Cd-contaminated soil by pot experiment.The results showed that the content of Cd in brown rice was 0.22 mg / kg,which was 53.19% lower than that in CK. |
PDF Full Text Request